Honda 400EX Top End Rebuild Part 1: Disassemble | Partzilla.com
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- เผยแพร่เมื่อ 27 ส.ค. 2024
- Get a spark plug socket and a compression tester for this step of the TRX400 top end rebuild: bit.ly/trx400ex...
This video shows you how to do a top end rebuild on a 4 stroke Honda 400EX ATV. The first of three videos in our 400EX top end rebuild series, this video covers top end disassembly including how to pull off the entire intake assembly, and how to remove the carburetor, exhaust, header pipe, top motor mount, cylinder head, cam chain tensioner, cam gear, and camshaft. You will also learn how to remove the cylinder from the piston and how to remove the piston.
See the piston diagram: www.partzilla....
See the cylinder head diagram: www.partzilla....
Next step is to assess our valves, rings, piston, and cylinder in part two: • 400EX Top End Rebuild ...
We’ll replace the valve stems and reassemble the top end in part three: • 400EX Top End Rebuild ...
Read how to do this part of the job step by step: www.partzilla....
VIDEO HIGHLIGHTS
Pull off entire intake system and carburetor - 6:23
Remove exhaust - 7:13
Remove header pipe - 7:28
Remove top motor mount and pull cylinder head - 7:49
Remove Cam Chain Tensioner (including bracket and negative cable), cam gear and camshaft - 8:24
Remove cylinder from the piston - 11:06
Remove piston (including piston pin clip and wrist pin) - 11:20
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In the video we’re working with a 2007 Honda TRX400 EX, but you may have similar steps for your Honda ATV. If you’re not sure whether these steps apply to your machine, leave a comment and we’ll get back to you.
RELATED CONTENT
TRX400EX top end rebuild playlist:
• Honda TRX 400EX Top En...
If I had not seen these videos I would have never even thought about replacing the head on my Honda xr400. Makes it feel familiar enough to tackle it. I'm going to go be it a try. Thank you.
How did it go?
Very good video series. I have done many ATV engines but never get tired of watching
a wonderful mechanic like John doing one!
Just so you know, I knew nothing about quads. Because of you I have confidence in everything I need to know. I even order parts from you, even if there a bit more costly because of the trust I have it doesn't matter. Thank you. Thank you
I bought a new one in 2001 and rode it almost 14 years before it began to smoke just a little. Thousands of miles on pavement plus all the off roading. It’s a hell of a engine
Hands down, the best instructional video.
You build lots of confidence for working on internals thanks!
Definitely most detailed video on yt helped me out alot
Great video for sure! Definitely a good trained mechanic! He isn't sugar coating the job. It's a fairly big one. Not case splitting transmission big job but still.
I get a lot of bikes in my home shop that peope started tearing into makes a mess amd upsets them and me plus cost them more money and time.
Excellent video, really helped me have the confidence to take mine apart for the first time
Great video helped a lot with my rebuild! One note, the cylinder head bolts are 12mm not 14mm.
Mine they are 14mm
Excellent video's very in depth and educating I'm doing mine today. Thanks you for taking the time to do them.
best instructional video ever though.
When you do the compression test mine showed about 85psi without wide open throttle. Then I went ahead and took out the carburetor and I tested the compression that way and it showed 130psi of compression. So I think it would be best to test compression with wide open throttle or without the carburator in place.
lol i knew what you meant the video really helped me tho thank you i used it to rebuild a honda i dont know what size but it was about the same size the wire on the chain trick was especially usefull 👍
Awesome Video!
Brilliant video !! thanks
Great video easy to follow properly explained thanks.
Awesome video
Awesome video, I will be rebuilding the top end on my 2001 Trx400Ex. Do you have a video on how to do a bottom end rebuild?
the hardest part of taking apart a honda most the time is the exhaust pipe lol
cool,I'm learning.
Awesome, Regulator! Thanks for watching
Can you not do like dirt bike and clean all subframe parts and loosen bottom 2 bolts and lift whole subframe away from the carb and all?
My2008 has been smoking a lot but still making around 139 pounds of compression I was really careful to not drop Andy thing and there’s litteraly no decompression pin? Anyone ever heard of this before
If you do another 400ex you should do like an hid headlight upgrade
We will add it to the list, but for now, we are more focused on maintenance and fixing mechanical issues rather than aftermarket upgrades. We will try to get to it.
Great video
I ran my Honda ex without oil now it's just taking when I'm trying to start it any information on what I can do to get it going again I put oil but it seems too late
Great video. My 03 is smoking and at least needs seals. So, In your opinion while it's apart should I do the 440 or stay with the 400. Reliability is my priority. Thx!!!
Stay with the 400. Ive seen a few cooked cranks due to a 440 kit.
Thank you. Just needed advice from a pro.
I have a Honda 400ex trx 2003 all it does is spins over bt it want start could you help I replace the coil and this cdi box bike still didn’t crank
Nice video,im curious as to why you didnt have the valves re lapped while u were already at the machine shop. Or even just hand lap them?
They all seated well, it's not always necessary to lap them.
I watched your video and did and while new top rebuild all new. And it’s dripping oil out the exhaust port we’re the exhaust pipes connect to the motor. What would be the cause?
How you easily remove the cam locater pins?
I couldn’t find the top dead center video
Nice video
Thanks, Hydar! Glad you liked it.
I have a Kawasaki bayou 220 4 stroke atv and when I start it smokes really bad. What can be causing this? Does it need a top end rebuild? New piston kit and gaskets?
Is this basically the same process you would do while installing a Wiseco 440 big bore kit (includes piston, sleeve, rings, wristpin, and gaskets )? Also, while I'm cracking the engine open, what other parts would you recommend replacing simply because I'm going to the trouble to open it already?
It's a 2007
Do you have to warm it up to take the top end off because mine won’t even start
Another great series thanks John. How tight does that compression test adapter go on? Looked to be just hand tight? Thx
yep finger tight is just fine for a quick compression test, just make sure the spark plug is tighter when re-installed.
Procedure will be same for honda xr400r motorcycle
I had to replace my valve cover gasket, I got the cover off but a missing dowl pin, what do I do?
My quad has that we change the oil n now it throws smoke
I have one question Sir, When you disassembled the top end when you took the 2 bolts off the cam sprocket didn't it make the motor go off TDC? and if you did take it apart with out it on TDC does it makes the valves all weird like some might be open? could you explain how it works. And how would you put it back together if it wasn't at TDC when you pulled it apart? Thanks Braden
You just put it to TDC and set timing on reassembly. Always better to reset timing to make sure it's accurate when you put it back together.
Do you have to set tdc when you’re only replacing a valve cover gasket?
No. Just remove the cover and replace.
I keep on having to rebuild my 400ex. From the piston rings. Because it smokes and burns the oil. This will be my 5th time having to replace them. Any idea. Why I'm tired of having to replace them after every time I go. Ride it for. Long periods of. Time. My guess is that is over heating some. How . I bought it with bad piston rings swaped them with a new +1 wiseco piston and rings and new block. There's nothing I think I'm doing wrong. Especially after doing it 5 time now plzzz. Help.
Let me guess after that start up its got 98 psi
Do yall have a top end piston kit for a 05 trx400FGA
great video
+JDG400EX Thank you Sir.
Partzilla what color was thr smokr mine is white just a bit but more when i rev it in nutral
Mine is leaking on the shift side by the header
@partzilla I'll have my piston, rings, and gaskets in tomorrow to rebuild my topend and I went with the stock 85mm bore. I bought the quad pushing oil out the head horribly but starts right up cold and idles, just smokes like a train due to oil literally being pushed into the headers. do you think these rings should solve my problem and should I have gone with a larger bore? the parts will be here tomorrow so I guess I'll know for sure then but this video has me worried I should have gone bigger
What part of the video makes you worried about going bigger? If it's a stock motor, then you go with stock size.
Would the process be similar for a 2005?
yes
Hey John, I've seen your video here and I'm curious about the range for compression on a 400EX. I have one here that is showing me over a hundred fifty. Is that considered excellent or what is the top-of-the-line it should be at? Is it too much? The bike fires right up but I just wanted to check the compression and it just seems pretty high so I don't know what size bore it is or if it has a kit on it. Wondering if you can give me a little break down of what would be the top of the line compression for this type of bike? Thank you
For a stock 400EX your compression test should be between 100 and 128psi. If there is engine work to it, that number may change...
John, great thank you very much, your videos are clear and helpful. You do an excellent job with explaining it 4 this old guy who is getting back into the game, now that the kids are grown. Thanks again and I hope to see some more videos from you John.
My 2002 400ex is reading 30psi :( haha I’m start taking everything apart tomorrow!! Website to buy all the parts?
www.partzilla.com
Great vid but I can't seem to find anywhere selling the cam bearings
The radial bearing can be found here.
www.partzilla.com/catalog/honda/atv/2007/trx400ex-a-trx400ex/camshaft-valve
Ok so I just replaced my head gasket got it all back together right I think and now it will only run when the choke is on did i do something wrong or is it a carb issue
Chances are it's a carb clean issue.
Great video this helped a lot
I have a 2005 400ex and it makes pecking/knocking noise. and gets worse when i gas on it. what could it be?
Most likely need a valve adjustment.
Do you have to re lap the valves or anything if your using the old valves or just put them right back where they was?
You don't have to relap the valves. You can, but it isn't always necessary.
Partzilla so if my valves look good and are seated good and not leaking I can just put them back in right?? Also in what situation would you have to re lap valve? Thanks for the help.
Only if there are deformities on the edge. If they seat well, you should be fine.
Классный канал😁
What is the metal ring between the top and the pistons and ring. Like a metal gasket.
Are you talking about #9 on the diagram? The metal o-ring?
www.partzilla.com/catalog/honda/atv/2007/trx400ex-a-trx400ex/cylinder
I made it down to the cylinder, all bolts are off but it's stuck on pretty good. How can I get it off? As of now I plan on taking a rubber mallet to it.
Double check that you aren't missing a bolt somewhere, it shouldn't be that difficult to pull off. Give it some solid pressure. If you have to use a rubber mallet, be gentle, only tap it enough to get it loose, don't wail on it like you're framing a house. Good luck!
Partzilla
Awesome, thanks. definitely could not have done this without the TRX400 youtube series!!
Collin, don't sell yourself short, you can do anything you set your mind to. We appreciate the awesome feedback either way. :)
Why can’t I remove the alley on the cam chain
On a 400ex If rear axle sides back and forth is there a nut loose or is carrier bearing junk
Have you checked the pinch bolts?
Where can I find the parts for that motor in Houston
Those camshaft allen key bolts wont come out and when i try to you real force the sprocket rotates as well taking it off of tdc? any suggestions
Break them loose, keep trying, then snug them down hand tight to reset your TDC.
What is that socket called I need one for my 400ex. If you can tell me the size and exact part. Thank you and love these videos.
+Rory Reyes Which socket are you referring to? If it is the spark plug, then it's this one: www.partzilla.com/parts/detail/honda/HP-89217-KB7-940.html
+Partzilla.com it's the spark plug socket and also will it fit my 2003 400ex. And thank you for the link.
+Rory Reyes Yes it will.
+Bryce Kelley thanks man I ordered mine a while ago still waiting for it to come also needed a new spark plug wire and ignition
+Rory Reyes Cool deal. 99% of the parts and engine components are the same for all years of the 400exs.
what year is the quad your working on... and are like most of the years the same
This unit was a 2007. Most of the years are the same for this model.
Any idea where I can get the 2 Alan head bolts that came off the sprocket for the cam chain?
Oem parts diagram on their site
www.partzilla.com/catalog/honda/atv/2007/trx400ex-a-trx400ex/cam-chain-tensioner
What should the compression be for a Honda recon 250?
Wide open throttle, right around 97 - 100psi.
My Bike is blowing thick white smoke out of the exhaust. I have a 2003 Honda trx400ex? Why is this
Normally white smoke is coolant, dark smoke is oil. In this case, since there is no coolant, you either took the TRX underwater and are burning off any water in the system or you are just burning oil and it looks white.
Partzilla would this mean bad rings, or new top end rebuild is needed?
Typically it would mean bad rings. Too much oil is getting past them into the cylinder and burning off.
Partzilla what would you suggest?
I would tear it down and rebuild. It will most likely get worse, not better.
I think my piston broke i need help where should i start
The only way to inspect it is to tear down the motor!
Can you hone the 400ex cylinder? Just want to make sure before I rebuild my bike.
You can, provided it's not worn too much.
@@PartzillaParts thanks
Do I have to have the motor at TDC before removing the top end and replacing it?
I always start out at TDC
Hojala estuviera en español! :(
Would this all be the same on a 2000 model trx400ex?
Also will the valve seals for a 2007 fit my 2000 model?
As far as I know, they didn't change a lot on the motor. I would confirm it on the diagrams before you bet on it though. Compare what you need between the two years and see if the part numbers match.
How do you rotate the can gear?
You have to turn the whole crank.
will the spark plug tool work on 05
Yes, it should. It's basically an 18mm thin wall socket.
hey did u replace the head bolts
No, it wasn't necessary.
Partzilla should you replace your intake an head bolts ,or is there a way tell if there good?
They are required to change unless they are damaged. Just inspect them. If they have bad threads, heavy corrosion or are bent in anyway, replace them. Otherwise, you should be fine.
not saying anything bad about u whearing gloves but if i was whearing gloves to fix my fourwheeler he would call me a pussy lol
He. Who is he? Why is he mean? When you spend the last 45 minutes of your day trying to scrub off grease and grime from working on vehicles, gloves start to earn a little more respect. #gloveshavefeelingstoo
hes not mean he just tells me to man up but being funny not trynna be mean
In that case, gloves are elastic, you can shoot them at him like a rubber band when he's funny. We are not responsible for any eye injury or choking hazard that may occur. :)
lol but thank you for the vid
You got it, Turtle. And you don't have to wear gloves if you don't want to. We still like you. It's all good either way. Thanks for watching!
lmao wth is a wrenchet?
ha! Wrenchet - Noun - 1. ratcheting wrenches. 2. Complete verbal slip up while filming a demonstration video. You may choose. :D